1. Field of the Invention
The present invention relates to a liquid crystal display device and particularly to a liquid crystal display device having a structure in which display quality is improved by an auxiliary capacitive electrode.
2. Description of the Related Art
For example, in an active matrix type liquid crystal display device, scanning lines and data lines are formed on a glass substrate in a X-direction and a Y-direction, respectively. In the vicinity of each intersection of the scanning lines and the data lines, a thin film transistor connected to both lines is provided as a switching element. An insulating film is formed thereon, and on the insulating film, pixel electrodes are formed to be connected the thin film transistors, which are provided near the intersections, through contact holes provided to the insulating film, respectively. In this case, the edge portion of each pixel electrode is overlapped with both lines in order to obtain a high aperture ratio.
The above-explained liquid crystal display device is disclosed in, for example, FIGS. 1 and 4 of Unexamined Japanese Patent Application KOKAI Publication No. H1-156725.
However, in the above-structured liquid crystal display device, since the edge portion of the pixel electrode is overlapped with the data lines, coupling capacitance occurs on the overlapped portion. For this reason, there is a problem in which vertical crosstalk resulting from the coupling capacitance occurs on the overlapped portion to degrade a display characteristic. In other words, for example, as illustrated in FIG. 24A, in a case where a black square 82 is displayed in one pixel 81 with a gray background, an electrical potential of the pixel 81 is varied as a drain voltage. Accordingly, as illustrated by reference numeral 83 of FIG. 24B, the background color of the upper and lower portions of the square 82 slightly deepens. In this way, the portion colored in black is pulled to the upper and lower sides of the square 82, so that the display characteristic will deteriorate.
In addition, it is assumed that the contents of Unexamined Japanese Patent Application KOKAI Publication No. H1-156725 are incorporated into this specification.